A Review of Three-Dimensional Scanning Near-Field Optical Microscopy (3D-SNOM) and Its Applications in Nanoscale Light Management

Abstract

Abstract:In this article, we present an overview of aperture and apertureless type scanning near-field optical microscopy (SNOM) techniques that have been developed, with a focus on three-dimensional (3D) SNOM methods. 3D SNOM has been undertaken to image the local distribution (within~100 nm of the surface) of the electromagnetic radiation scattered by random and deterministic arrays of metal nanostructures or photonic crystal waveguides. Individual metal nanoparticles and metal nanoparticle arrays exhibit unique effects under light illumination, including plasmon resonance and waveguiding properties, which can be directly investigated using 3D-SNOM. In the second part of this article, we will review a few applications in which 3D-SNOM has proven to be useful for designing and understanding specific nano-optoelectronic structures. Examples include the analysis of the nano-optical response phonetic crystal waveguides, aperture antennae and metal nanoparticle arrays, as well as the design of plasmonic solar cells incorporating random arrays of copper nanoparticles as an optical absorption enhancement layer, and the use of 3D-SNOM to probe multiple components of the electric and magnetic near-fields without requiring specially designed probe tips. A common denominator of these examples is the added value provided by 3D-SNOM in predicting the properties-performance relationship of nanostructured systems.

Direct molecular-level near-field plasmon and temperature assessment in a single plasmonic hotspot

“…The near-field optical response is, however, strongly localization-dependent and its amplitude is directly related to atomic-scale features at the surface of the plasmonic structure 1,8 . Techniques that have been shown to efficiently spatially map the plasmon energy of SERS substrates with sub-nanometre-scale resolution include scattering scanning near-field optical microscopy 9 , (although the possibility of artefacts and misinterpretation remains high) 10 , photoemission electron microscopy 11 , and electron energy loss spectroscopy 12 . This spatial mapping is required to investigate the impact of atomic-scale features on plasmonic and molecular response interpretation 1,8 .…”

Plasmon response evaluation based on image-derived arbitrary nanostructures

“…A proper understanding of the parameters affecting the amplitude and the frequency of the plasmon resonance, as well as the specific modes involved at a particular wavelength is a key prerequisite for reaching well-defined and desired plasmonic characteristics.In a perfect scenario, time consuming and costly experimental trial-and-error experiments should thus be avoided and replaced by a detailed theoretical description of the electric field enhancement and its spatial distribution for any plasmonic system under investigation (unless complex techniques such as electron energy loss scattering or scattering near field optical microscopy are used to map the spatial distribution of the field intensity). [6][7][8] The plasmon resonance simulated is then linked to the expected Raman response, although several theories and other factors also come into play. [9][10][11] Unfortunately, tremendous computational capacity and calculation time are generally unavoidable when it comes to predicting the specific behavior of plasmonic substrates.…”

THz Pulsed Imaging in Biomedical Applications

“…Driven by technological advances, a plethora of new modern diagnostics systems is investigated and validated, as complementary biomedical techniques to the conventional ones, covering various scales, from macromolecules to tissues/organs. Among them, worthy of special mention are: infrared (IR) imaging [1,2], scanning near-field microscopy [3,4], photoacoustic microscopy [5], ultrasonic imaging [6], optical coherence tomography [7,8], digital holography microscopy [9][10][11], Raman scattering microscopy [12], Coherent Raman Scattering (CRS) spectroscopic imaging [13][14][15][16][17][18][19][20][21][22][23], two-photon fluorescence (TPF) [19,24] and second-harmonic generation (SHG) imaging [25][26][27], and super-resolved imaging techniques [28][29][30][31].…”